Manufacture or treatment of artificial materials



Patented Mar. 30, 1937 MEAN"UFACTUR,E 0R TREATMENT OF TI- FIGIAL'MATERIALS Henry Dreyfus, London, England 'No Drawing ApplicationFebruary 4, 1936, Serial 1 l No. 62 ;330.: :{In'Great Britain March 7,11935 13 Claims. (01. 18-7-54 This invention relates to improvements inthe production and treatment of artificial materials and particularly'toimprovements in processes wherein artificial filaments, threads," yarns,foils and similar materials are formed by wet spinprocesses and/or arestretched. This in- .vention is a-continuation-in-part of the inventiondisclosed in application S. No. 638,179 filed Octosber v, 1932- 0Processeshave hitherto been described wherein artificial filaments,threads, yarns, ribbons, foils and similar materials having a basis oforganic derivatives of cellulose are produced by the extrusion ofsolutions of organic derivatives vv15 of cellulose into coagulatingmedia comprising mixtures ofsolvents or other swelling agents andnon-solvents :for the cellulose derivatives. Processes have also beendescribed wherein artificial filaments, threads, yarns, ribbons, foilsand .similar materials having a basis of organic derivatives ofcellulose are softened by mixtures of solvents or other swelling agentsand non-isolvents for the cellulose derivatives 311613 8178 stretchedwhile in the softened condition.

It has now been discovered that-improved re- :sults may be obtained insuch processes by apply- ;ing to the materials an acid salt whichdecreases the solubility of the'solvent or other swelling .agent .inthenon-solvent. The term .acid salt?- is employed in the presentspecification to mean 1Q. salt which has an acid reaction in solution,and does not-necessarily mean a polybasic acid salt which still containsreplaceable hydrogen.

According to the present invention, therefore, in processes whereinartificial filaments, threads, yarns, ribbons, foils and similarmaterials having a basis of organic derivatives of cellulose are treatedwith mixtures of solvents or other swelling agents and non-solvents forthe cellulose derivatives, there are applied to such materials in thepresence of such mixtures acid salts which are adapted to decrease thesolubility of the solvents or other swelling agents in the nonsolvents.-It,has been found thatthe presence of acidsal-ts-causes more rapid orgreater softening of the materials. The term "swelling agent "for ,thecellulose derivative as used hereinafter is to be understood asincluding both true solvents and also agents which exert only-a swellingaction. The invention is of-particular, importance where the mixture'ofswelling agent and nonsolvent with which the materials are treated is anaqueous solution of an organic swelling agent for the cellulosederivative. Y

The acid salts :employed according to this csuitable concen-tration1;.c;ause:.-a tu se aratiq One f the principal acid, salts according tothe present invention ,is

invention are preferablyhighly soluble in the non-solvent constituent ofthe medium and substantially insolublein the swelling agent constituent'of the mediumr The salts may be salts of either organic or inorganicacids and among suitable salts which maybe employed may be mentioned thelammonium,-gsodium Jand potasdihydrogen phosphates, :bisulphates and bisulphites "which are acidic in reaction; the chloridesxzof zinc andmagnesium, acid-sodium 10 and potassium'acetates and other acid salts10f alkali metals or ammonia with like fatty acids, and acid salts of.polybasic :organicacids, as. :sodium and potassium hydrogen .tartratesand acidsodium and potassium citratesand oxalates. The; invention may becarried into effect in a number-of -ways.- Thusya solution of an organicderivative :of cellulose' in -a neutral organic vso'lvent may beextruded into a coagulating medium consisting of a'strongsolution-preferably aqueous, of a swelling agentfor thecellulosederivative which contains an acid salt or againa solution of anvorganicderivative of cellulose in a neutral organic medium containing aswelling agent for thescellulose derivative of higher boiling point thanthe non-solvent-of.ithezcoagulating medium may be extruded into; acoagulatin medium :consisting :of-a solution-poi a swelling agent inwatervorother: non-solvent containing an acid-salt. :vBy employing aswelling agent :in the. coagulating medium whichhis less volatile thanthe non-solvent .:constituent of the :coagulating medium :products ofhigh lustre may be obtained. The concentration of swelling agent in thecoagulatingmedium wil-lwary-with the conditions of spinning. Whenspinning acetone solutions of-cellulosewacetate highly satisfactoryresults may, in genera-l be obtained with aqueous coagulating mediaconsisting of 25 to 65%, and particularly 45 to solutions of suchsolvents as diacetone alcohol, diethylltartrate and ethyllactate.hqacidsalt maybe-employed in any ovided ,that it .does not of theswelling agent from. the non-solvent. I- ngeneraL, proportions of 1 to10% are rsatisfactory e .g., 3,,5 or 8%. 'iy-Artificial' filaments andother products produced by wet spinning processes ,inay also 'be broughtto a highly softened condition sub- ;sequent tobut continuously withcoagulation by treatment withrnedia containing swelling agents and acid;salts, .andistretched whilein such softenedcondition. v advantages ofthe use of that materials produced by wet spinning processes may bestretched continuously with their production very rapidly and to a highdegree, e. g. to 500 or 1,000% or more of the length which they wouldhave if no stretch were applied.

As indicated above the present invention is also of very great value inprocesses for stretching formed artificial filaments, threads, yarns,ribbons, foils and similar materials containing organic vderivatives ofcellulose, wherein the materials are treated with mixtures of swellingagents and non-solvents in order to soften them prior to stretching. Theacid salts may be incorporated in the mixtures of swelling agents andnon-solvents applied to the materials or the salts may be applied to thematerials separately while they are carrying the mixture of swellingagent and non-solvent. Where the salt is applied separately it ispreferable to apply it in solution in a non-solvent medium, thenonsolvent being the same as that present in the medium on thematerials. Preferably the swelling agent constituent of the mediumemployed to soften the materials is less volatile than the non-solventconstituent.

The stretching operation may be carried out in any suitable manner, forexample, the materials may be stretched by. means of positively drivenrollers or the like. Filaments, yarns, and like materials may be treatedin the form of hanks, but it is preferable to treat the materials whilethey are travelling from onepoint to another, e. g. from bobbin tobobbin, from a spinning machine to the winding apparatus, or as a warpproceeding from beam to beam. The stretching operation may be carriedout in a single stage, but is preferablyeifected in a number of stages,with or without intermediate stages in which the 'materials are releasedfrom the stretching tension. The concentration of the swelling agent inthe softening medium applied to the materials may vary in accordancewith the degree of softening which is required, and the nature of theagent employed. However, in general, concentrations of 25 to 65%,

and particularly of to of swelling agent are satisfactory. The quantityof the salt applied to the materials may vary but should not be so greatas to cause actual separation of the solvent and non-solvent; Ingeneral, proportions of 1 to 5, 8 or 10% of the weight of thesolvent/non-solvent mixture present are satisfactory.

The invention is broadly applicable to the treatment of materials towhich there are applied mixtures of swelling agents and nonsolvents. Anysuitable swelling agents and nonsolvents may be employed. Thus, forexample, suitable solvents are acetone, diacetone alcohol, ethyllactate, diethyl tartrate, dioxane or esters and ether esters of olefineglycols, e. g. glycol mono-acetate and methyl glycol mono-acetate andother neutral solvents. Whilst, as indicated above, it is preferablethat the non-solvent should be water, other non-solvents may be employedif desined, e. g. ethers, alcohols and hydrocarbons.

The process of the present invention may be effected atnormaltemperatures and pressures or atjj'super-atmospheric temperaturesand/or jpressuresje; g. temperatures of 40 to C. or .mqrggfand pressuresof 10 to 30 pounds per square inch or more above atmospheric pressure.Stretching may be eflfected to only a. low

degree, e .g. to or 200% of the original length of the materials, or to:considerably higher degrees, e. g. to 400 or 600% or more of theoriginal length of the materials.

The lustre of the materials produced according to this invention may bevaried, for example by varying the concentration or nature of theswelling agent employed in the coagulating bath or in the medium appliedto soften the materials-the lustre of the products varying, according tothe conditions, from very high lustre to matt or non-lustrous. Theconcentration of the acid salt employed also affects the lustre of theproducts, the lustre, in general, increasing with the concentration ofthe salt. It is found that products having a low lustre producedaccording to this invention are not relustred by treatments with saltsor solvents such as are described in U. S. Patents Nos. 1,808,098 and1,774,184. I

The following examples illustrate the invention but are not tobeconsidered as limiting it in any way:-

Example I A 25% solution of cellulose acetate in acetone is spun throughorifices of 0.08 mm. diameter into a coagulating bath consisting of 45parts by weight of diacetone alcohol, 8 parts by weight of sodiumbisulphate and 47 parts by weight of Example II Cellulose acetate yarnsare withdrawn from a creel of bobbins and passed in warp formation, i.e. as a sheet of yarns in substantially parallel formation, through abath consistingof 50 parts by weight of dioxane, 47 parts by weight ofwater and 2 parts by weight of acid sodium acetate, and. are stretchedwhilst in such bath, by means of a device extending across the entiresheet to 2, 4 or'more times their original length.

0n emerging from the bath the yarns are washed, dried and again wound onto bobbins.

Whilst the invention is particularly valuable in the production andtreatment of artificial filaments and similar materials having a basisor cellulose acetate, and has been described above with specialreference thereto, it may also be directed to the production andtreatment of artificial materials having a basis of any other organicderivative of cellulose, e. g. cellulose formate, propionate, butyrate,nitroacetate and other esters or mixed esters of cellulose, methyl,ethyl and butyl celluloses and other cellulose ethers, mixed ethers andmixed ether esters, for

example ethyl cellulose acetate and oxyethyl cellulose acetate.

Having described my invention what I desire to secure by Letters Patentis: l

1. In processes wherein artificial filaments, threads, yarns, ribbons,foils and similar materialshaving'a basis of an organic derivative ofcellulose are treated with a mixture of a swelling agent andanon-solvent for the cellulose derivative, the step of subjecting thematerials in the presence of said mixture to treatment" with a polybasicacid salt which contains replaceable hydrogen, which has an acidreaction in solution and which is adapted to decrease the solubility ofthe said swelling agent in the said non-solvent.

2. Process for the manufacture of artificial filaments, threads, yarns,ribbons, and similar materials, which comprises extruding a solution ofan organic derivative of cellulose through a suitable shaping deviceinto a coagulating medium containing a swelling agent and a non-solventfor the cellulose derivative and treating the extruded materials with apolybasic acid salt which contains replaceable hydrogen, which has anacid reaction, and which decreases the solubility of the said swellingagent in the said non-solvent.

3. Process for the treatment of artificial filaments, threads, yarns,ribbons, and similar materials having a basis of an organic derivativeof cellulose, which comprises softening such materials by treating themwith a mixture of a swelling agent and a non-solvent for the cellulosederivative and with a polybasic acid salt which contains replaceablehydrogen, which has an acid reaction, and which decreases the solubilityof the said swelling agent in the said non-solvent, and subjecting thesoftened materials to a stretching operation.

4. Process for the manufacture of artificial filaments, threads, yarns,ribbons, and similar materials, which comprises extruding a solution ofan organic derivative of cellulose in a neutral organic solvent mediumthrough a suitable shaping device intoa coagulating medium containing anon-solvent for the cellulose derivative, a less volatile neutralorganic swelling agent therefor in a concentration of 25-65% and apolybasic acid salt which contains replaceable hydrogen, which has anacid reaction, and which decreases the solubility of the said swellingagent in the said non-solvent, and stretching the products.

5. Process for the treatment of artificial filaments, threads, yarns,ribbons, and similar materials having a basis of an organic derivativeof cellulose/which comprises softening such materials by treating themwith a mixture of a nonsolvent for the cellulose derivative, a neutralorganic solvent therefor in a concentration of 25-65% and a polybaslcacid salt which contains replaceable hydrogen, which has an acidreaction, and which decreases the solubility of the said solvent in thesaid non-solvent, and subjecting the softened materials to a stretchingoperation.

6. Process for the manufacture of artificial filaments, threads, yarns,ribbons, and similar materials, which comprises extruding a solution ofan organic derivative of cellulose in a neutral organic solvent mediumthrough a suitable shaping device into an aqueous coagulating mediumcontaining a neutral organic solvent for the cellulose derivative, whichis less volatile than water, in a concentration of 25-65% and 1-10% of apolybasic acid salt which contains replaceable hydrogen, which has anacid reaction, and which decreases the solubility of the said solvent inwater, and stretching the products.

7. Process for the treatment of artificial filaments, threads, yarns,ribbons, and similar materials having a basis of an organic derivativeof cellulose, which comprises softening such materials by treating themwith an aqueous solution of a neutral organic solvent for the cellulosederivative in a concentration of 25-65% containing 1-10% of a polybasicacid salt which contains replaceable hydrogen, which has an acidreaction, and which decreases the solubility of the said solvent inwater and subjecting the softened materials to a stretching operation.

8. Process for the manufacture of artificial filaments, threads, yarns,ribbons, and similar materials, which comprises extruding a solution ofcellulose acetate in acetone through a suitable shaping device into'anaqueous coagulating medium containing -55% of a neutral organic solventfor the cellulose acetate which is less volatile than water and 1-10% ofan acid salt selected from the group consisting of the dihydrogenphosphates of sodium, potassium and ammonia, and stretching theproducts.

9. Process for the treatment of artificial filaments, threads, yarns,ribbons, and similar materials having a basis of cellulose acetate,which comprises softening such materials by treating them with anaqueous solution containing 45-55% of a neutral organic solvent for thecellulose acetate and 1-10% of an acid salt selected from the groupconsisting of the di-hydrogen phosphates of sodium. potassium andammonia, and subjecting the softened materials to a stretchingoperation.

10. Process for the manufacture of artificial filaments, threads, yarns,ribbons, and similar materials, which comprises extruding a solution ofcellulose acetate in acetone through a suitable shaping device into anaqueous coagulating me- I dium containing 45-55% of a neutral organicsolvent for the cellulose acetate which is less volatile than water and1-10% of an acid salt selected from the group consisting of thebisulphites of sodium, potassium and ammonia, and stretching theproducts.

11. Process for the treatment of artificial filaments, threads, yarns,ribbons, and similar materials having a basis of cellulose acetate,which comprises softening such materials by treating them with anaqueous solution containing 45-55% of a neutral organic solvent for thecellulose acetate and 110% of an acid salt selected from the groupconsisting of the bisulphites of sodium, potassium and ammonia, andsubjecting the softened materials to a stretching operation,

12. Process for the manufacture of artificial filaments, threads, yarns,ribbons, and similar materials, which comprises extruding a solution ofcellulose acetate in acetone through a suitable shaping device-into anaqueous coagulating medium containing 45-55% of a neutral organicsolvent for the cellulose acetate which is less volatile than water and1-10% of an acid salt comprises softening such materials by treatingthem with an aqueous solution containing 45-55% of a neutral organicsolvent for the cellulose acetate and 1-10% of an acid salt selectedfrom the group consisting of the bisulphates of sodium, potassium andammonia, and subjecting the softened materials to a stretchingoperation.

HENRY DREYFUS.

